btrfs as default filesystem for F22?

Josh Boyer jwboyer at fedoraproject.org
Mon Oct 6 12:49:50 UTC 2014


On Mon, Oct 6, 2014 at 8:29 AM, Gene Czarcinski <gczarcinski at gmail.com> wrote:
> On 10/05/2014 08:25 PM, Josh Boyer wrote:
>>
>> On Sun, Oct 5, 2014 at 3:03 PM, Gene Czarcinski <gczarcinski at gmail.com>
>> wrote:
>>>
>>> On 10/05/2014 09:50 AM, Josef Bacik wrote:
>>>
>>> On Oct 2, 2014 11:32 PM, "Andre Robatino" <robatino at fedoraproject.org>
>>> wrote:
>>>>
>>>> openSUSE 13.2, scheduled for release in November, will have btrfs as the
>>>> default filesystem. What are the chances that F22 will follow suit,
>>>> assuming
>>>> openSUSE has no major problems with it?
>>>>
>>>> https://news.opensuse.org/2014/09/22/
>>>>
>>> My plan is to push for F23, I'm still wrapping up some balance bugs and
>>> some
>>> other issues we've found at work and then this will be my next priority.
>>> Suse benefits from having a narrow "supported" criteria, like only use it
>>> with lots of space and don't use any of the RAID stuff, plus they have
>>> two
>>> kernel guys on it and Dave Sterba who is now in charge of btrfs-progs.
>>> Fedora unfortunately has me who has Facebook work to do and Eric who is a
>>> professional fs juggler. We will get there, and when we do it will be
>>> less
>>> painful than its going to be for Suse since they will have fixed it all
>>> for
>>> us ;).  Thanks,
>>>
>>>
>>> F23 sounds about right to me.  I am very much a fan of BTRFS and
>>> currently
>>> use it on all of my systems with few problems but I think that F22 is a
>>> bit
>>> early to make it the default.
>>>
>>> However, I do believe that there a couple of things that need to happen
>>> to
>>> make thjings easier/better:
>>>
>>> 1.  The Fedora developers/maintainers need to take BTRFS more seriously
>>> and
>>> address btrfs related problems seriously and quickly.  Yes, I know that
>>> BTRFS swap draining is a little bit difficult to deal with when you are
>>> up
>>> to you rear end in alligators but, a little more attension please.
>>
>> Nope.  See, we deal with what we think we can deal with and what is
>> impacting the most people.  There are two of us.  A non-default
>> filesystem with a lot of known issues isn't high on the priority list.
>> If you would like to see more attention on btrfs, find some people
>> that share your interest to triage and work on the bugs (which are all
>> upstream bugs) or chip in yourself.
>
> Nope, I understand.  However, what I said is with the understanding to
> change to using BTRFS as the default ... whenever it takes place and I stand
> by my statement of needing more attention as a requirement.

The attention needed is a prerequisite for it to even remotely be
considered for default.  I'm explaining the people working on the
kernel aren't staffed to give that attention, so if people would like
btrfs to be the default filesystem in Fedora they need to start
working on it now.

>>> 2.  Currently anaconda supports supports installation of /boot on BTRFS
>>> either as a simple directory on a BTRFS volume (yes, I don't understand
>>> why
>>> someone would do this but ...), as a simple directory on a rootfs ("/")
>>> subvolume, or as a spepate subvolume.  Grub2.02 also supports this and
>>> grubby will support if "real soon now" when pjones can get enough time to
>>> examine and integrate my grubby patches adding BTRFS support.
>>
>> This isn't a requirement for btrfs by default.  It's a nice to have.
>
> Using btrfs by default needs more users to want to use it.  Making it easier
> for more users to install into btrfs will see increased use.  It will also
> demonstrate that Fedora development/maintenance is paying attention to
> BTRFS.

Um... sure?  Except nobody cares if /boot is btrfs or not.  It's a
nicety that results in btrfs being the main fs in use for the system,
but it isn't a requirement.  You can use it for the rootfs and for
home just fine without /boot being btrfs.  (It's also somewhat of a
pipe dream, given that the EFI system partition is never going to be
btrfs and that's another mountpoint under /boot.)

> Now, there is another question which has not been voiced: what is the "plan"
> for filessystems in Fedora (and by implication RHEL)?  Is it BTRFS?  Or,
> perhaps is it LVM with XFS?  IIRC, some time ago it was stated that the plan
> was to move to BTRFS.  It is not clear to me that everyone is onboard with
> that decision.  Or, perhaps that decision is being reconsidered.

Depends.  There is no single grand unified plan for Fedora
filesystems.  Believe me, if there was that would be amazing.

Workstation would like to use btrfs for a number of nice desktop
technologies (like easy backups, time slider, etc).  It's not ready,
so WS stuck with the existing default of ext4.  We discussed (briefly)
following SuSE's approach and limiting the features possible with
btrfs, but after discussing with Josef we decided to forego that as
well.  There are alternatives that could be used (like dm snapshots)
but the userspace work wasn't going to happen for F21 in any case.

Cloud uses ext4.  I don't believe they have any benefit to switching
to any other filesystem so it doesn't matter to them.

Server already switched to using XFS as the default fs, which makes
sense given that RHEL 7 defaults to XFS.  I believe btrfs remains a
Technology Preview in RHEL7.  My take on that is that it is never
going to be default for RHEL 7 or even move out of Tech Preview, but I
have no real idea.  I also have no idea what RHEL 8 will bring as I
don't work on RHEL and even if I did I wouldn't be talking about it at
this point.

As for being onboard with any sort of decision, it basically boils
down to being able to prove that btrfs is ready to be the default FS,
and being able to support it in that manner.  Right now neither are
the case.

>>> Anyway, we are getting close.
>>
>> If it's getting close, it's entirely because of Josef's and the SuSE
>> team's efforts.  They should be applauded.
>>
> Yes, they should!  But Fedora moving to increased use of BTRFS seems to be
> receding at the speed of time: it is always a couple of releases from now;
> go away I am busy with other stuff.  Sorry is this bothers some people but
> that is the impression I get.

It's always a couple releases away because btrfs is always a couple of
bugs/issues away from being ready.  Your impression doesn't  bother
me, but it's slightly wrong.  It's not "go away, I'm busy".  It's "I'm
busy, if you want to make this happen please find people to put in the
work to make it so."  There's a difference there that's worth
noticing.

josh


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